Production of alkali-metal nitrate



Patented Jan. 22, 1929.

UNITED STATES PATENT orrics.

"WILHELM WILD AND CHBISTOPH BECK, F LUDWIGSHAFEN-ON-THE RHINE, GER- MANY, ASSIGNOBS TO I, G. FABBENINDUSTRIE AK'IIENGESELLSCHAFT, 0F FRANK- FORT-ON-THE-HAIN, GERMANY, A CORPORATION OF GERMANY.

PRODUCTION OF ALKALI-HETAL NITRATE.

ll'o Drawing. lpplication filed Bay 12, 1927, Serial No. 190,968, and in Germany July 8, 1928.

The specification of the German Patent No. 390,791 describes a process for the production of alkali metal nitrates by the action of nitric acid, or nitrogen oxids on alkali metal chlorid c solutions. From the resulting alkali metal nitrate 7 solution the hydrochloric acid is simultaneously driven out and the nitrogen oxids contained in the gaseous mixture, escaping during the expulsion of the hydrochloric l0 acig, are recovered by means of sulphuric aci We have now found that it is particularly advantageous in the aforesaid manufacture of alkali metal nitrates to carry out the treatment of the escaping gaseous mixture with sulphuric acid under pressure. In these circumstances, the absorption of the nitrous gases is effected more easily and quickly while on the other hand, contrary to expectation,

the solubility of the hydrochloric acid in sulphuric acid is not appreciably increased, in spite of the higher partial pressure. In

carrying out the process under pressure, the

work can be performed, in considerably smaller a paratus and with smaller quantities of su phuric acid than when. working at atmospheric pressure. The pressure employed may have any desired height; for example it may amount to 2, 5, 10, 20 or even more atmospheres.

The following example will further illus- EwampZa-A gas mixture resulting from the said production of alkali metal nitrates and containing 90 per cent of nitrogen, 6 per cent of oxygen, 1 per cent of nitrogen oxids and 3 per cent of hydrogen chlorid is treated, under a pressure of 6 atmospheres, with concentrated sulphuric acid. A solution of nitroxyl-sulphuric acid in sulphuric acid containing up to 5 per cent of nitrogen in the form of nitroxyl-sulphuric acid (at a higher concentration nitroxyl-sulphuric acid would crystallize out), but at the same time only at the utmost 0.025 per cent of hydrogen chlorid is obtained.

We claim I 1. In the production of alkali metal nitrate from alkali metal chlorids and nitric acid, the step of freeing the resulting gas mixture containing nitrogen oxids and hydrogen chlorid from the nitrogen oxids by treatment with sulphuric acid under a pressure higher than atmospheric pressure.

2. In the production of alkali metal nitrate from alkali metal chlorids and nitric acid, the step of freeing the resulting gas mixture containing nitrogen oxids and hydrogen chlorid 6U from the nitrogen oxids by treatment with sulphuric acid under a pressure of 6 atmospheres.

In testimony whereof we have hereunto set our hands.

trate how this invention may be carried out in practice, but the invention is not limited to this example.

WILHELM WILD. CHRISTOPH BECK. 

